1. Field of the Invention
The present invention generally relates to a wireless mesh network for use in a Wireless Local Area Network (WLAN). More particularly, the present invention relates to an apparatus, method and system for routing a broadcast data frame that can avoid redundant routing of a broadcast data frame to be transmitted and received in each mesh point within a wireless mesh network with multiple mesh portals.
2. Description of the Related Art
A wireless mesh network provides a new paradigm to wireless network markets in a ubiquitous age. The wireless mesh network is a type of multihop ad-hoc network based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11s standard in which fixed and mobile nodes are connected by radio links such that the high speed Internet can be supported for a specific city or area. The wireless mesh network is a wireless solution very suitable for a wide area such as a university campus where installation of a conventional Wireless Local Area Network (WLAN) is difficult and premises of a stadium, port, airport, park, shopping mall, museum, and center of a city are difficult for the installation of a cable.
The conventional mesh network is provided with multiple mesh points and multiple mesh portals acting as nodes for communicating with an external node such as an external network or bridge. In the following description, the term “node” is the generic term used for every access point forming the mesh network and every access point connected to the mesh network.
Conventionally, only one mesh portal is present in the mesh network. However, IEEE 802.11s currently being standardized supports multiple mesh portals in the mesh network. When receiving a packet, each of the mesh portals determines whether a destination of the received packet is outside or inside the mesh network. If the destination is inside the mesh network, the mesh portal forwards the packet to inside of the mesh network. If the destination is outside the mesh network, the mesh portal forwards the packet to outside of the mesh network. Accordingly, the mesh portals know information about all nodes within the mesh network and can detect a connection of a new node through a registration process for a mesh point that newly joins the mesh network.
When the multiple mesh portals are present in the mesh network, each mesh point transmits a packet only to its default mesh portal in order to limit data frame traffic to be transmitted and received between the mesh points and portals in the form of broadcasting, according to the IEEE 802.11s standard. Every mesh point of the mesh network selects and registers its default mesh portal through a registration process. When a broadcast data frame is transmitted to a network outside the mesh network, it is forwarded only to a registered default mesh portal. Thus, because the mesh portal processes only a unicast data frame specified and received, it only processes the data frame received from the mesh point. When the mesh portal receives a data frame unspecified, the data frame received from the mesh point is discarded.
In this case, a problem exists in that an advantage of the mesh network technology capable of distributing and transmitting traffic cannot be taken, since the default mesh portal is only used even when the multiple mesh portals are present in the network.
On the other hand, when a broadcast data frame is transmitted from outside to inside of the mesh network, redundant routing occurs due to frame broadcasting by the multiple mesh portals and frame broadcasting by the mesh points receiving the frame broadcasting in the prior art. That is, since the broadcast data frame has an “ALL” value in a destination address field for forwarding to all the mesh points, the mesh points perform redundant broadcasting of the same frame broadcast received from one or more mesh portals. Since there is a problem in that network traffic significantly increases while broadcast data frames are looped in the worst case, multiple mesh portals are not allowed in the IEEE 802.11s standard.
Accordingly, there is a need for an improved apparatus, method and system which can prevent redundant routing of a broadcast data frame and also can reduce network traffic by taking an advantage in use of the multiple mesh portals when the multiple mesh portals are present in the wireless mesh network.